This application is based on, and claims priority to, British patent application number 9926555.5, filed Nov. 9, 1999, and which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method and apparatus for orienting flexible walled articles, for example, of the pillow bag type such as snack packs.
2. Description of the Related Art
Many food stuffs, particularly snacks, are packaged in flexible walled articles which are then loaded into larger cartons or the like for transportation. Recently, transparent xe2x80x9ccartonsxe2x80x9d have been developed into which the snack packs are loaded for sale as complete cartons. In this case, it is desirable to ensure that each pack is oriented in the same way within the carton both for aesthetic reasons and to enable a purchaser to view at least part of the packs through the wall of the carton. It is also helpful in other applications to ensure that the packs are loaded into cartons in the same orientation for ease of checking that there are no rogue packs of a different type.
Up until now, this process has been largely manual with a human packer receiving a sequence of packs for manually loading into cartons. Recently, a device was disclosed which can distinguish between a xe2x80x9clandscapexe2x80x9d or xe2x80x9cportraitxe2x80x9d orientation of a rectangular pack and then rotate it to a required orientation automatically. However, this overlooks or ignores the fact that a typical rectangular pack will have printing on each side and so can take up more than one portrait or landscape orientation. In particular, packs typically carry marking which differ between the front and back of the pack.
Accordingly, it is an object of the present invention to provide a method and apparatus for efficiently and effectively orienting flexible walled articles.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, objects of the present invention are achieved by providing a method and apparatus for orienting flexible walled articles. In the method and apparatus, the orientation of a pattern on the article is detected. Then, the detected pattern is used to control any required turning process for turning the article. Thus, the present invention does not rely simply on detecting the physical orientation (for example, portrait or landscape) of the article, but upon the orientation of the pattern. In this way, articles which would appear to conventional systems to have the same orientation, but which in fact are reversed or upside down, can be distinguished.
Surprisingly, according to embodiments of the present invention, it has been determined that sufficiently accurate pattern recognition can be performed despite the fact that the article has flexible walls and thus is not guaranteed to present its surface to a pattern detector in exactly the same way on every occasion.
A variety of pattern matching techniques can be used. In one approach, according to an embodiment of the present invention, the pattern over the entire surface of the article facing the pattern detector is determined, for example, using a CCD camera. This determined pattern is then compared with a set of predetermined patterns to determine the orientation of the article.
In other approaches, however, each pattern is defined by the appearance of a number of image areas along the presented surface of the article. Thus, the pattern detected may only be a portion of the overall pattern since it has been found that this is often sufficient to distinguish between the different orientations of the article. This is particularly so if there are only a limited number of possible orientations, such as four or eight, which will usually be the case. Furthermore, according to an embodiment of the present invention, some very simple pattern matching processes have been developed, particularly for snack packs, which can be performed very quickly to thereby enable fast processing speeds to be achieved of, for example, one-hundred-twenty (120) articles per minute or more.
According to embodiments of the present invention, two primary techniques have been developed for comparing the detected pattern with predetermined patterns. In one technique, the appearance of each image area is defined by more than one channel of data, each channel representing a different characteristic of the appearance of the image area. One or more of these channels can then be used to make a comparison with the corresponding channel of a predetermined pattern. Conveniently, this comparison is achieved by simply determining the difference between the data values of the two sets and summing the differences.
In another approach, a comparison can be performed by combining the channels into a single channel and then comparing the single channel with each corresponding single channel of each predetermined pattern.
An orientation system could be provided by a single orientation device which is operable to carry out whichever turning operation(s) is(are) required. For example, the article could be fed to a robotic device. Alternatively, however, the orientation system may comprise a first orientation device for imparting a 90xc2x0 lateral rotation to the article, a second orientation device for imparting a 180xc2x0 side to side rotation to the article, and a third orientation device for imparting a 180xc2x0 end to end rotation. Separating the orientation system into three devices allows the article to be fed through the apparatus substantially continuously by a conveyor or the like.
The second orientation device could comprise a double twisted band utilized with a bypass path so that if a side to side rotation is not required, the article is not fed to the band. The third orientation device could comprise an abutment such as one or more fingers which can be selectively positioned in the path of the article, and a pushing device for flipping the article over the abutment.
Embodiments of the present invention are particularly applicable to articles of the pillow bag type such as, for example, snack packs containing, for example, potato chips, hula hoops and the like. These types of packs are typically created by a form-fill sealing machine such as, for example, a vertical form-fill sealing machine. An Apex packaging machine manufactured by Ishida Co., Ltd, is an example of such a machine.